The invention relates to a mounting method of a tunnel arch. The mounting method includes the steps of S1, using a transportation device to transport a plurality of arch sections to the preset position in a tunnel; S2, providing an arch trolley and using the same to mount the arc sections to form an arch, wherein the arch trolley comprises a trolley body and an operation unit, the trolley body comprises a chassis and a travelling gear, a power unit used for providing power to the trolley body and the operation unit is arranged on the chassis, the operation unit comprises a first operation arm and a second operation arm which are telescopic, the bottom of each of the first operation arm and the second operation arm is connected to the chassis, a manipulator used for clamping the arch sections is arranged at the tail end of the first operation arm, and a clamping mechanism and/or a gripper mechanism used for clamping and/or griping the different arch sections is arranged at the tail end of the second operation arm. By the above mode, construction efficiency can be improved.